Furnace not switching on


Old 10-21-02, 05:41 PM
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Angry Furnace not switching on

Weel it is getting into that season and we have recently turned the old furnace on.

it has been working fine until now...
The thermostat is switching on but the furnace isn't.

The pilot light is lit and the fan is running but the burner isn't coming on to heat the air?

Any ideas?


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Old 10-21-02, 05:47 PM
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inside cabinet of furnace for resettable saftey switches. these look like a disc with 2 wires attached, button in the middle, one may be popped. when is the fan running? when you put it to heat or when you turn the fan on? what make/model is it?
Old 10-21-02, 06:11 PM
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Re: check

Originally posted by hvac4u
inside cabinet of furnace for resettable saftey switches. these look like a disc with 2 wires attached, button in the middle, one may be popped. when is the fan running? when you put it to heat or when you turn the fan on? what make/model is it?
There doesn't seem to be any safety switches that require reseting, and I've done a check on the wires from the thermostat down to the furnace, and there is continuity. Something that strikes me as strange though, is that there is gas burning around the thermocouple next to the pilot light. In fact, I can light the gas around the thermocouple without lighting the pilot light! I've turned the whole works off, and I'm going to wait for it to cool and clean out the area between the thermocouple and pilot light, perhaps something is directing gas in there, and shouldn't.
I used to work at a gas fireplace company, and from what I recall there, the thermocouple was only there to ensure that the pilot light was lit in order to allow the main gas flow through, so if the thermocouple was overheating that wouldn't quite make any sense. Perhaps the thermocouple has gotten too hot and is damaged? Sorry for the rambling, I'm kind of thinking as a write.

Old 10-21-02, 06:40 PM
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If the thermocouple is damaged, the gas valve would shut down and shut off the gas to BOTH the pilot and main burners. Why is the fan running? See if the fan/limit control is causing the fan to run full time. If the fan/limit control is defective, it could cause the fan to run full time and also prevent voltage from getting to the gas valve.
Old 10-21-02, 08:36 PM
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My Two Cents Worth

Hello: tif22

As a benefit to you, it would much more effective to read as many of the recently posted questions pertaining to heaters. Within them almost every problem has been replied to in fully detail.

A very detailed & comprehensive list of just about all the potential problems and possible solutions are posted in a question named "Gas Furnace Problem." Topic date is 10/14/02.

Reading that topic and the many others contained herein pertaining to Gas Furnaces should provide you with a positive solution to the problem your currently having with your heater.

Others Suggestions:
Read several postings within this forum on the topic of "Gas Furnace Problems." The questions already asked describe like or similarly related problem descriptions as your question.

These prior postings and any or all the replies offered within them contain almost all the required information needed pertaining to the many potential and or possible problems with most heating units like or similar to the one your describing.

Additional Suggestions:
Read the manufacturers online web site for product information, problem possibilities, causes and solving methods, part locations, disassembly, reassembly methods, repair procedures, instructions, pictorials, schematics, all or part of which may be available online.

An excellent source for orginal replacement parts is your local retail appliance parts store. Appliance parts dealers test and carry replacement parts for all appliances. Parts dealers are listed in the phone book under appliances.

Retail parts dealers can also help determine what the possible problem may be. Bring the make, model and serial numbers if you stop in at the store. The info will help to determine some if not all the possible problem causes.

Regards & Good Luck, Forum Host & Moderator.
TCB4U2B2B Company Enterprises. Energy Conservation Consultants & Gas Appliance Diagnostics Technicians.

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